Charge costs, not showing correct price?

Gone to settings>home charging.

Set my rate per kWh to 0.07 as my unit price is 7 pence a kWh. I've applied that too all my charges, but when I look at the pricing it doesn't show what it should show? 

For example last night I used 9.28 kWh. Its telling me the charge cost was £2.21. 

By my math that should be 0.07*9.28 = 0.64. So shouldn't that be 0.64p

While I'm at it whats the difference between used 9.28kWh in this charge and added 8.88kWh... does that mean it added 8.88 kWh to the battery, but it took 9.28kWH for precondition, sentry etc from the grid?